Work phase determination method for machine tools, and device therefor

ABSTRACT

In adjusting phase for work (W), the operation of mounting/dismounting a reference tool on a spindle ( 6 ) is dispensed with and so is a storage space for the reference tool, and besides, it is arranged that the thrust on the work (W) does not directly act on the spindle ( 6 ) at the time of this phase adjustment. In a machine tool in which a spindle housing ( 7 ) supporting the specifically directed spindle ( 6 ) for rotation alone is supported for parallel motion in orthogonal three-axis directions (XYZ) by a numerical control mechanism ( 4 ), in determining the phase for the work (W) is feed-rotated around a specific axis (S), it is arranged that with a reference block ( 9 ) fixed to the spindle housing ( 7 ), the work (W) is feed-rotated around the specific axis (S) to abut the phase reference section (W 1 ) of the work against the reference block ( 9 ), so as to find the amount of feed-rotation of the work at the time of this abutment.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the priority under 35 U.S.C. 119 ofJapanese Patent Application No. 2002-312178, filed Oct. 22, 2002, whichis hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to a work phase determination method for machinetools with spindles and a device therefor.

BACKGROUND OF THE INVENTION

There is a machine tool in which a spindle housing supporting aspecifically directed spindle for rotation alone is supported forparallel motion in orthogonal three-axis directions XYZ by a numericalcontrol mechanism (see, for example, Japanese Patent Publication No.2001-9652).

In the machine tool, a work support-feeding device that feed-rotates awork around a specific axis is provided, and machining is carried out byfeed-rotating the work at a specific angle position therearound.

To perform such a machining, it is necessary to accurately determine aphase for the work around the specific axis on the work support-feedingdevice. Therefore, a reference tool for phase determination is formedand installed on the spindle, and thereon, a phase determinationoperation is performed so as to abut the work. After the operation, thetool is detached from the spindle and stored in a specific position.(See, for example, Japanese Patent No. 3083776.)

In the above-mentioned conventional work phase determination method,working efficiency falls because the operation of mounting/dismountingthe reference tool on the spindle is required. In addition, it isuneconomical because a storage space for the reference tool is required.Moreover, there is some fear of shortening bearing life because a loadacts on a bearing rotatably supporting the spindle when the work abutsthe reference tool.

The present invention aims to solve the above-mentioned problems.

SUMMARY OF THE INVENTION

To achieve the above-mentioned aims, in the process according to thepresent invention, in a machine tool having a spindle in which a spindlehousing supporting the specifically directed spindle for rotation aloneis supported for parallel motion in orthogonal three-axis directions XYZby a numerical control mechanism, in determining the phase for the workto be feed-rotated around a specific axis, it is arranged that with areference block having plane faces, fixed to the periphery of the frontend of the spindle housing so as to protrude forward a little from thefront end of the spindle housing, the work is feed-rotated around thespecific axis to abut a phase reference section of the work against thereference block, so as to find the amount of feed-rotation (a phaseangle θ of a chuck part) of the work at the time of this abutment.

In this invention, the reference block remains fixed on the spindlehousing, and such a construction can be simple and inexpensive. Inaddition, when operating so as to determine a phase around the specificaxis of the work, force is not transmitted from the work to the spindle.Accordingly, the bearing life for rotatably supporting the spindle canbe prolonged.

More specifically, the reference block, which is fixed right under thespindle so as to protrude forward a little from the front end of thespindle housing, is provided with a first plane face perpendicular to adirection of the spindle and a second plane face parallel to both of thedirection of the spindle and the specific axis. In determining the phasefor the work to be feed-rotated about the specific axis, the work isfeed-rotated around the specific axis in a first direction and/or anopposite second direction to abut the phase reference section of thework against one or each of the first plane face and the second planeface, so as to find the amount of feed-rotation (phase angles θ1, θ2 ofthe chuck part) of the work at the time of the abutments.

In this invention, the following effect is realized in addition to theabove-mentioned effects. That is, the accuracy of the determination of aphase for the work around the specific axis by using the first planeface and the second plane face is improved.

In this invention, a crankshaft is suitable as the work, and in thiscase, a crank pin can be used as the phase reference section. Accordingto this, the above-mentioned effects can be realized in thedetermination of the phase for the crankshaft, and besides, using thecrank pin for the phase reference section can dispense with preparing aspecial phase reference section.

In the device according to the present invention, in a machine tool inwhich a spindle housing supporting a specifically directed spindle forrotation alone is supported for parallel motion in orthogonal three-axisdirections XYZ by a numerical control mechanism, a reference block whicha phase reference section of a work feed-rotated around a specific axisby the numerical control mechanism abuts is fixed on the referenceblock. The device contributes to carrying out the process according tothe invention.

More specifically, in the machine tool in which the spindle housingsupporting the specifically directed spindle for rotation alone issupported for parallel motion in orthogonal three-axis directions XYZ bythe numerical control mechanism, the reference block is fixed at aspecific position in relation to the spindle, on the spindle housing,whereas a work support-feeding device for feed-rotating the work aroundthe specific axis perpendicular to the direction of the spindle, and awork phase deciding means for determining a phase for the work aroundthe specific axis based on the amount of feed-rotation around it whenthe phase reference section feed-rotated around it abuts against thereference block displaced to a phase adjustment position with referenceto the work in advance are provided. This aspect of the inventioncontributes to understanding the amount of feed-rotation of the work byreciprocally rotating the work around the specific axis.

In this case, the work support-feeding device comprises an intermediatetable, rectangular in plan, fixed horizontally, a work driving tablefixed on an end of the top face of the intermediate table, and a pushtable fixed on the other end thereof. In addition, the work drivingdevice has an NC table installed to have a table main body fixed on theintermediate table, and besides, has a driving center for supporting achuck portion supported on the table main body and rotatively drivenaround a specific axis of the X-axis direction by the NC table and arotation center of an end face of the work grasped by the chuck portion.Moreover, the reference block is constructed as follows. That is, thereference block in the present invention is fixed to protrude forward alittle from the front end of the spindle housing with a spindle and isprovided with a first plane face perpendicular to the direction of thespindle and a second plane face parallel to both the direction of thespindle and the specific axis.

In this invention, the phase for the work around the specific axis isdetermined by abutting the phase reference section of the work againsteither of the first plane face and the second plane face. Besides, whenthe phase reference section of the work is abutted against both of thefirst plane face and the second plane face, the phase for the workaround the specific axis can be determined accurately regardless of anyerror in its finishing dimension.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a machine tool with a spindle of the presentinvention, in which a part is shown in a section.

FIG. 2 is a plan view of the machine tool, and FIG. 3 is a view showinga section taken on line X1-X1 in FIG. 2.

FIG. 4 is a view showing a first portion of an operating flow sheet ofthe present invention, and FIG. 5 is a view showing a second portion ofan operating flow sheet that connects at “A” to the portion of theoperating flow sheet of FIG. 4.

FIG. 6 is an explanatory view showing a situation in which a crank pinabuts the first plane face of a reference block of the machine tool.

FIG. 7 is an explanatory view showing a situation in which a crank pinabuts the second plane face of the reference block.

FIG. 8 is an explanatory view of a modification concerning a phaseadjustment position of the reference block.

PREFERRED EMBODIMENT OF THE PRESENT INVENTION

An explanation about the present invention will follow with reference tofigures.

In FIGS. 1 to 3, 1 is a bed, and thereon are provided a fixed column 2,a work support-feeding device 3, a numerical control mechanism 4 andhydropneumatic equipment 5.

A cylindrical spindle housing 7 supporting a longitudinally directedspindle 6 (in a Z-axis direction) for free rotation is mounted on thefixed column 2 in a feed-displaceable manner in an X-axis direction, aY-axis direction and the Z-axis direction, which form orthogonalthree-axis directions. A cutting tool 8 is fixed to a front end of thespindle 6.

A reference block 9 is fixed to the lowest position of a front outerperipheral face of the spindle housing 7 below the spindle 6 to protrudeforward. The reference block 9 comprises a front face 9 a and a lowerend face 9 b. Here, the front face 9 a forms a first plane faceperpendicular to the Z-axis direction, and the lower end face 9 b formsa second plane face parallel to both of the Z-axis direction and theX-axis direction.

The work support-feeding device 3 comprises a horizontal rotating table12, an intermediate table 13, a work drive table 14 and a center pushtable 15. The rotating table 12 is feed-rotated around a Z-axialdirected rotation support axis 11 by a servomotor 10 provided to the bed1. The intermediate table 13 is horizontally fixed on the rotating table12. The work drive table 14 is fixed on one end side of an upper face ofthe intermediate table 13, and the push table 15 is fixed on the otherend side thereof.

In this case, the work drive table 14 is provided with a table main body17, a chuck portion 18 and a driving side center 19. The table main body17 is fixed to the intermediate table 13 and has a NC (numericalcontrol) table 16 installed. The chuck portion 18 is supported on thetable main body 17 to be rotatively driven around a specific axis S inthe X-axis direction by the NC table 16. The driving center 19 issupported on the table main body 17 and located on the specific axis S,supporting a rotating center of an end face of a work w grasped by thechuck portion 18. The chuck portion 18 has a plurality of claws 18 a forgrasping a work as shown in FIG. 3.

The center push table 15 is provided with a table main body 20 fixed tothe intermediate table 13, a drive device 20 a of the X-axis directionmounted on the table main body 20 and a push center 21. The push center21 is slidably-displaceably supported on the table main body 20 andpush-moved by the drive device 20 a to support the rotating center ofthe other end face of the work w.

In the above-mentioned machine tool, an example of operations before acrankshaft of the work w is started to be machined will be explainedwith reference to FIGS. 4 to 7. Here, FIG. 4 and FIG. 5 show twoportions of an operating flow sheet. FIG. 6 is an explanatory viewshowing a situation in which a crank pin w is point-abutted against thefirst plane face 9 a of a reference block 9. FIG. 7 is an explanatoryview showing a situation in which the crank pin w is point-abuttedagainst the second plane face 9 b of the reference block 9.

First, in step S100, necessary data about the shape of the work w,position of the reference block 9 and programs for determining a phaseand for machining the work w are input from an input device of thenumerical control mechanism 4. Here, the numerical control mechanism 4has these data memorized on its memory portion.

Next, in step S101, the numerical control mechanism 4 has the servomotor10 operate as necessary. That is, the rotation support axis 11 isfeed-rotated, the horizontal rotation table 12 rotates, and the twocenters 19, 21 are positioned on the specific axis S. Besides, the NCtable 16 is operated as necessary, and therefore, the chuck portion 18is feed-rotated, and a radial line of the chuck portion in agreementwith a table phase reference p0 is made a phase zero position referencek1 thereof as shown in FIG. 3. Here, the phase zero position referencek1 is an imagined one fixedly specified on the chuck portion 18, and thetable phase reference p0 is an imagined one fixedly specified on thetable main body 16.

Thereafter, the work w is loaded between the centers 19, 21 by a robot,an automatic feed device or manual controls and the like, and itsposition is temporarily kept. In this case, although care is taken thatthe phase of the work w around the specific axis S and the phase of thechuck portion 18 therearound closely resemble each other, it is not doneto accurately match these phases because the loading must be donerapidly. Accordingly, the phase zero position reference k1 of the chuckportion 18 and a phase reference k2 of the work w (a work phasereference) are usually shifted somewhat relative to one another aroundthe specific axis S. In this example, the work phase reference k2 isshifted from the phase zero position reference k1 of the chuck portion18 to the side opposite the rotation of the chuck portion 18 by an angleθ0. Here, the phase reference k2 is an imagined one fixedly specified onthe work w.

Next, in step S102, the drive device 20 a displaces one center 21 towardthe other center 19 and puts these centers 19, 21 into center holescomprising conical female faces formed in end faces of the work w,respectively. Therefore, the work w is supported by the centers 19, 21,and thereafter, the work w is released from the keeping position due tothe robot, the automatic feed device or the manual controls and the likeso as to protect the circumference thereof from the next operation.Then, the drive device 20 a has the center 21 push toward the center 19by further strong force. Therefore, the work w is surely put between thecenters 19, 21 to have the rotation center agree with the specific axisS exactly. In addition, at the same time, one end face of the work w ispushed toward a work longitudinal reference face 18 b formed near thecenter of the chuck portion 18 and perpendicular to the specific axis S,and the position on the specific axis S direction is fixed. Under thissituation, the claws 18 a clamp the outer periphery of one end of thework w.

Thereafter, in step S103, the program for determining a phase isstarted. The numerical control mechanism 4 displaces the spindle housingto the predetermined position, and the reference block 9 is displacedand stopped at the phase adjustment position p2. In the displacedreference block 9, the center in the X-axis direction is positioned atabout the center of the length of a specified crank pin w1. Besides, asshown in FIG. 6, an intersection point p3 between the first plane face 9a and the second plane face 9 b is turned to a radial direction of thespecific axis S and situated on the Z-axis and the Y-axis to bepositioned on a line L1 inclined in right rise by 45° against theseaxes. Moreover, the first plane face 9 a and the second plane face 9 bare respectively positioned on a rotation displacement locus of thecrank pin w1 around the specific axis S. Besides, the phase adjustmentposition p2 showing an example can be exchanged to another positionsuitably. This will be described later in detail.

Next, in step S104, the NC table 16 is operated to feed-rotate the workw in a normal rotation direction around the specific axis S with thechuck portion 18. When the crank pin w1 abuts the first plane face 9 aof the reference block 9 as shown in FIG. 6, the abutment is detected tostop the NC table 16 from operating. In this case, the rotation angle θ1of the chuck portion 18 at the time of this abutment is recognized andmemorized in the numerical control mechanism 4. The rotation angle θ1 isthe angle from the table phase reference p0 to the phase zero positionreference k1 of the chuck portion 18 at the time of the abutment.

In this case, the abutment between the crank pin w1 and the first planeface 9 a is detected directly by a torque sensor when torque transmittedfrom the work drive portion 14 to the chuck portion 18 increases orindirectly by drive amperometry of the work drive portion 14.

Next, in step S105, it is discriminated whether a highly accurateoperation will be required in the operation of determining the phase forthe work. In this case, the standard for discrimination depends on theoperator's judgement.

When it is decided that the highly-accurate operation is unnecessary,the process is displaced to step S106, whereas when it is decided thatthe operation is necessary, the process is displaced to step 107.

In the step S106, the rotation angle of the work w in after adjustingthe phase is corrected in accordance with the rotation angle θ1 of thechuck portion 18 at the time of the abutment between the reference block9 and the crank pin w1.

Specifically, the rotation angle θ1 is calculated by data such as arotation radius around the specific axis S at the center of the crankpin w1, the diameter of the crank pin and the position of the firstplane face 9 a of the reference block 9. Here, the calculated rotationangle from the table phase reference p0 of the chuck portion 18 isassumed to be θ10.

Next, the rotation angle θ10 is deducted from the rotation angle θ1 ofthe chuck portion 18 calculated in the step S104. This calculateddifference value θ12 agrees with the angle θ0 from the work phasereference k2 to the phase zero position reference k1 of the chuckportion 18 if there is no machining error. And this is handled as aphase shift angle between the chuck portion 18 and the work w, and madethe amount of correction in determining the phase for the work w.Accordingly, a rotation angle θt of the chuck portion 18 for determiningthe phase for the work w, such as rotating the work phase reference k2from the table phase reference p0 by a specified angle θw only, iscalculated by the following formula (1). Here, the rotation angle θt isthe angle through which the phase zero position reference k1 of thechuck portion 18 rotates from the table phase reference p0 in the normalrotation direction f1.θt=θw+θ 12  Formula (1)

According to the formula (1), when positioning the work w at the placeof an optional specified angle θw in the after work machining, therotation angle θt requires the size obtained by adding the differencevalue θ12 to the angle θw. This operation is automatically carried outby the numerical control mechanism 4.

In the case of determining the phase for the work w like this, when theshape data input into the numerical control mechanism 4 exactly agreewith the actual work w, the phase for the work w around the specificaxis S can be exactly determined. However, for example, when thediameter of the crank pin w1 is different from the input shape data, anerror is caused in proportion to the difference. In addition, when thereare unintentional irregularities on the periphery of the crank pin w1,an error is caused in proportion to the dimensions thereof in the radialdirection.

On the other hand, when the operation is displaced to step S107, thefollowing operation will be carried out.

The NC table 16 is operated in the reverse direction to the case in thestep S104, and the work w is feed-rotated with the chuck portion 18 in areverse rotation direction f2 around the specific axis S. And, when thecrank pin w1 abuts to the second plane face 9 b of the reference block 9as shown in FIG. 7, the abutment is detected, and thereafter, theoperation is stopped. A rotation angle θ2 from the table phase referencep0 of the chuck portion 18 at the time of the abutment is recognized andmemorized in the numerical control mechanism 4. The rotation angle θ2 isan angle from the table phase reference p0 to the phase zero positionreference k1 of the chuck portion 18 at the time of the abutment.

In this case, the abutment between the crank pin w1 and the first planeface 9 a can be detected in the same way as in the case of the stepS104.

Next, in step S108, an angle value θ3 is calculated by dividing thevalue adding the rotation angle θ1 in the step S104 and the rotationangle θ2 in the step S107 by 2.

Lastly, the operation is displaced to step S109, and therein, the anglevalue θ3 is memorized in the numerical control mechanism 4, and basedthereon, the rotation angle of the work w in after determining the phasefor the work w can be corrected.

More specifically, the rotation angle θ2 of the chuck portion 18 at thetime of the abutment between the reference block 9 and the crank pin w1in the step S108 is calculated by data such as the rotation radiusaround the specific axis S at the center of the crank pin w1, thediameter of the crank pin w1, and the position of the first plane face 9a of the reference block 9. Here, the calculated rotation angle from thetable phase reference p0 of the chuck portion 18 is assumed to be θ20.

Next, a difference value θ22 is calculated by adding the rotation angleθ20 and the rotation angle θ10, dividing it by 2, and subtracting thedivided angle value from the angle value θ3. The value θ22 accuratelyagrees with the angle θ0 from the work phase reference k2 to the tablephase reference p0 when the phase zero position reference k1 of thechuck portion 18 agrees with the table phase reference p0. Therefore,the value θ22 is handled as the phase shift angle between the chuckportion 18 and the work w to be made the amount of correction indetermining the phase for the work w. Accordingly, the rotation angle θtof the chuck portion 18 for an operation to determine the phase for thework w, such as rotating the work phase reference k2 from the tablephase reference p0 by a specified angle θw only, is calculated by thefollowing formula (2).θt=θw+θ 22  Formula (2)

According to formula (2), when positioning the work w at the place of anoptional specified angle θw in the after work machining, the rotationangle θt requires the size obtained by adding the difference value θ22and the angle θw. This operation is automatically carried out by thenumerical control mechanism 4.

In this operation, even if the diameter of the crank pin w1 is differentfrom the shape data input into the numerical control mechanism 4, thework w can be positioned in the place of a desired angle θw withoutbeing influenced by the error. Even if the crank pin w1 is machined in asection of polygonal shape by a crankshaft mirror or has unintentionalirregularities on the periphery, the degree of influence that the errorof the diameter of the crank pin w1 exerts on positioning the work w tothe place of the desired angle θw is greatly reduced. Therefore, thework w is positioned at the place of the desired angle θw moreaccurately than in the case of the step S106.

In the operations at all steps of the above-mentioned example, it can besuitably decided which operations will be operated by hand and whichoperations will be automatically carried out.

A modification of the above-mentioned example will be explained asfollows with reference to FIG. 8 and the like. Here, FIG. 8 is anexplanatory view showing a modification concerning a phase adjustmentposition p2 of the reference block 9.

(1) In the above-mentioned example, the intersection point p3 of thereference block 9 is turned to the radial direction of the specific axisS and situated on the Z-axis and the Y-axis to be positioned on the lineL1 inclined in right rise by 45° against these axes. In this case,although the correction amount in determining the phase for the work wcan be calculated only by displacing the reference block 9 to the phaseadjusting position p2 at a time, this method is not necessarily the mostaccurate. Therefore, to improve the accuracy in determining the phasefor the work, the operations may as well be performed as follows.

That is, as shown in FIG. 8, the reference block 9 is arranged in theplace where the periphery of the crank pin w1 point-abuts the firstplane face 9 a when the work phase reference k2 agrees with the tablephase reference p0, and the operation in the step S104 is carried out todetect the rotation angle θ1 of the chuck portion 18. In addition, thereference block 9 is arranged in the place where the periphery of thecrank pin w1 point-abuts the second plane face 9 b when the work phasereference k2 rotates from the table phase reference p0 to the reversaldirection f2 by 270°, and the operation in the step S1107 is carried outto detect the rotation angle θ2 of the chuck portion 18.

According to this, one end p4 of the specified diameter line d1 of thecrank pin w1 abuts the first plane face 9 a and the other end p5 thereofabuts the second plane face 9 b. Accordingly, an error in the diameterdirection of the crank pin w1 is surely eliminated, thereby improvingthe accuracy for determining the phase for the work w.

(2) In the step S104, although the difference value θ2 is calculated bypoint-abutting the periphery of the crank pin w1 against the first planeface 9 a, the periphery may be point-abutted against the second planeface 9 b instead of the first plane face 9 a.

(3) When calculating the rotation angles θ1 and θ2 of the chuck portion18, the reference block 9 can be arranged at a suitable place exceptingthe above-mentioned position within the range of the present invention.

According to thus constructed invention, the following effects can beachieved.

The usual operation of mounting/dismounting the reference tool on thespindle 6 is dispensed with, thereby improving the work efficiency. Inaddition, the usual storage space for the reference tool is dispensedwith, thereby achieving an inexpensive structure. Moreover, since theforce of the work w does not directly influence the spindle 6, the lifeof the bearing for supporting the spindle 6 can be prolonged.

Furthermore, the following effects can be realized in addition to theabove-mentioned effects. The accuracy for determining the phase for thework w can be improved by using the first plane face 9 a and the secondplane face 9 b. For example, even if the finishing accuracy of thediameter of the crank pin w1 is different from every work w, the phasefor the work w can be decided exactly. In addition, for example, even ifthe work w includes the crank pin w1 machined by the crankshaft millerto be microscopically shaped in a polygon, the phase for the work can bedecided accurately.

In addition, also in determining the phase for the crankshaft w1, sucheffects can be achieved. Moreover, the phase for the crankshaft w1 canbe decided without a special phase reference section by using the crankpin w1 as a work phase reference section.

Furthermore, the phase for the work w around the specific axis S can bedecided easily and flexibly by using the first plane face 9 a or thesecond plane face 9 b. In addition, it can be decided accurately inspite of any finishing dimension error of the phase reference section w1of the work w by abutting the phase reference section (the crank pin w1)of the work w against both of the first plane face 9 a and the secondplane face 9 b.

1. In a machine tool in which a spindle housing supporting aspecifically directed spindle for rotation is supported for motion by anumerical control mechanism, in determining a phase of a work to befeed-rotated around a specific axis, a work phase determination methodfor machine tools comprising: fixing a reference block to the spindlehousing of the spindle, said reference block comprising a first planeface, installing an NC table of the numerical control mechanism on awork support-feeding device, feed-rotating the work around the specificaxis, and correcting a rotation angle of the work in accordance with arotation angle of the NC table at a time of an abutment between a phasereference section of the work and the reference block.
 2. In a machinetool in which a spindle housing supporting a specifically directedspindle for rotation is supported for motion by a numerical controlmechanism, a work phase determination device comprising: a referenceblock fixed below and in vertical alignment with the spindle, thereference block having a first plane face perpendicular to a directionof the spindle and a second plane face parallel to both the direction ofthe spindle and the specific axis; a work support-feeding devicecomprising an intermediate table having a top face with opposite ends, awork driving table fixed on one end of the top face of the intermediatetable, and a center push table fixed on the other end thereof, said workdriving table having an NC table and a table main body fixed on theintermediate table; a chuck portion, supported on the table main body,rotatively driven around a specific axis in an X-axis direction by theNC table; and a drive center supported on the table main body andpositioned on the specific axis, the drive center supporting a rotationcenter of an end of a work grasped by the chuck portion, the work havinga phase reference section, wherein, in feed-rotating the work around thespecific axis, a rotation angle of the work is corrected in accordancewith a rotation angle of the NC table at a time of an abutment betweenthe phase reference section of the work and the reference block.
 3. Awork phase determination method for machine tools as set forth in claim1, wherein said reference block is arranged below and in verticalalignment with the spindle, at the lowest position of the spindlehousing.
 4. A work phase determination method for machine tools as setforth in claim 1, wherein said first plane face is perpendicular to afirst direction of the spindle, said reference block has a second planeface parallel to both the direction of the spindle and the specificaxis, and the work is feed rotated in either a first direction or asecond, opposite direction around the specific axis to abut the phasereference section of the work against either or each of the first planeface and the second plane face, so as to find the amount offeed-rotation of the work at the time of the abutment.
 5. A work phasedetermination method for machine tools as set forth in claim 4, whereinthe work is feed rotated in both the first direction and the second,opposite direction around the specific axis to abut the phase referencesection of the work against each of the first plane face and the secondplane face, so as to find the amount of feed-rotation of the work at thetime of the abutment.
 6. A work phase determination method for machinetools as set forth in claim 1, wherein the rotation angle of the work iscorrected in accordance with a rotation angle of the NC table at a timeof an abutment between a phase reference section of the work and saidfirst plane face of the reference block.
 7. A work phase determinationmethod for machine tools as set forth in claim 1, wherein said spindlehousing is supported for parallel motion in orthogonal three-axisdirections XYZ by the numerical control mechanism.
 8. A work phasedetermination device as set forth in claim 2, wherein said spindlehousing is supported for parallel motion in orthogonal three-axisdirections XYZ by the numerical control mechanism.
 9. A work phasedetermination device as set forth in claim 2, wherein the rotation angleof the work is corrected in accordance with a rotation angle of the NCtable at a time of an abutment between a phase reference section of thework and said first plane face of the reference block.